Through a last-minute compromise, the Legislature passed a change in state law that opens the door to using student performance as a measure for teacher and principal evaluation.

The change is a small, but important one. In the near term, it makes Maine a contender for federal funds through the competitive Race to the Top grant program run by the U.S. Department of Education.

In the long run, it could make Maine schools better, by providing teachers with meaningful feedback about what works and what doesn’t work in the classroom.

Passage of the law in the face of opposition of the Maine Education Association, the state’s largest teachers’ union, was far from certain, until a final amendment gave the MEA a seat on the task force that will design the assessments.

Teachers have put forward many valid reasons why student progress as measured by testing should not be their only performance standard. Not all students come to school ready to learn, they say, and demographic differences can play out in standardized test scores.

Or a student’s score in third-grade may have more to do with his first-grade teacher than his current one. But no argument suggests that measuring student progress should never be part of evaluating a teacher.

Since so much learning goes on privately between the teacher and student, it stands to reason that charting a student’s progress could give schools guidance about which techniques are working.

Maine’s history of education reform is nothing to be proud of. More than a decade after making the Learning Results law, we still don’t have a standards-based high school diploma. Modest pilot programs to create a small number of innovative charter schools keep hitting political brick walls.

Other states are moving faster and are showing results in the classroom, as well as making themselves eligible for more federal help, such as the Race to the Top program. Maine can choose to take part in this movement, or continue to squabble about dwindling resources.

The passage of the teacher evaluation law is a step in the right direction, but only if it signals a departure from the foot-dragging that has characterized education reform in Maine.